HTML中pre和textarea可以显示预格式化的文本。即保留空格和换行符。而不必添加<br>和 等HTML元素来添加换行和打印空格。
pre去掉滚动条
pre显示文本内容时是不会自动换行的，此时可以添加一些CSS来解决：
<pre>ourjs this is very very very very very very very very very very very very very very very logn contents.</pre>
pre {
word-wrap: break-word;
white-space: pre-wrap;
pa
